During fabrication of a semiconductor device, various processes are performed on a semiconductor wafer to form microelectronic components on the wafer. The processes may include chemical mechanical polishing (CMP), electroplating, and wet etching, as well as other conventional semiconductor processes. Each of these processes may be performed by individual processing equipment. Consequently, many pieces of processing equipment may be needed to fabricate semiconductor devices.
CMP equipment operates to planarize a layer of a semiconductor wafer by chemically and mechanically removing uneven topographic features of the wafer. A conventional CMP technique involves polishing the surface of a semiconductor wafer with a rotating polishing pad using a slurry of colloidal particles in an aqueous solution. The slurry promotes planarization of the wafer surface by producing a chemical reaction with the wafer surface and by providing abrasives to “grind” the wafer surface with the polishing pad. In certain applications, the polished semiconductor wafer may need to be further polished using a slurry with finer abrasives. Thus, in these applications, a second piece of CMP equipment needed to further polish the polished semiconductor wafer.
Electroplating equipment operates to deposit a metal layer onto a semiconductor wafer by electrolysis. With typical electroplating equipment, a target semiconductor wafer is immersed in a bath of plating solution or an aqueous metal acid solution, which includes a counter electrode. When the target semiconductor wafer is negatively charged and the counter electrode is positively charged, the positively charged metal ions in the plating solution are attracted to the cathode, i.e., the negatively charged wafer, and the ions are deposited on the wafer as a metal film.
Wet etching equipment operates to selectively remove materials from a semiconductor wafer. Wet etching may involve immersing a semiconductor wafer into a bath of chemical etchant, which dissolves unwanted materials from the wafer. Alternatively, the chemical etchant can be applied to the surface of a semiconductor wafer by spraying the etchant onto the wafer. Wet etching is typically used to remove exposed areas a semiconductor wafer that are not protected by a masking layer.
For fabrication of certain semiconductor devices, two or more pieces of the above-identified processing equipment may be needed to sequentially process semiconductor wafers. Since each piece of equipment may require a substantial amount of valuable real estate in a cleanroom, the total amount of space occupied by the equipment can be significant. Furthermore, since each piece of processing equipment may have different throughputs, the semiconductor wafers being processed may encounter congestion at one or more pieces of processing equipments.
In view of the above concerns, there is a need for a system and method for processing semiconductor wafers using different semiconductor processes so that the amount of space required in a cleanroom is reduced and congestion at one or more semiconductor processing stations of the system is eased or eliminated.